Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer).

In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

nature.com Subject Pages

User tools

Orexin

Definition

Orexin (also known as hypercretin) is a neuropeptide hormone produced in the hypothalamus. It influences sleep and arousal, appetite and energy expenditure, and defective orexin signalling is associated with narcolepsy.

Orexins (hypocretins) are involved in a large variety of behaviors and physiological processes including feeding, sleep/wake regulation, and reward. In this perspective, the authors propose a unifying function for orexins in translating motivational activation into sets of processes that support adaptive behaviors.

Recent data have shown that orexins regulate not only wakefulness but also feeding, emotional behaviour, reward seeking and autonomic and endocrine responses. Takeshi Sakurai summarizes these findings and proposes that the orexin system regulates the response of the body to its internal and external environments to support various motivated behaviours.